Expandable or inflatable packers are well known in the oil industry and have been used for decades. These packers are used to block the flow of fluids through the annular space between the pipe and the wall of the adjacent well bore or casing by sealing off the space between them and are placed in a well bore to isolate different zones of interest or production.
Casing packers can be employed to seal the annular space between the casing and the well bore. Packers can also be set inside the casing to restrict the flow of fluid in the annular space between the casing and production tubing. Packers can be permanent or retrievable. Packers can also be used singly or in combination with other packers to provide sealing engagement within the well bore or casing.
Expandable packers have historically been used for zone isolation, gas/oil ration control, straddle pack services, formation treating, testing and simlar operations. Expandable packers conform to the surface of the open hole and anchor the tool against differential pressure during operation. Expandable packers are especially well suited for setting in uncased holes or in old or pitted casing where slips would cause damage or failure of the surrounding casing. Furthermore expandable packers can seal in larger holes and in rough or irregularly shaped holes where compression type packers of the same nominal size would not otherwise seal.
Typically, expandable packers are inflated by fluid pressure in the tubing. Inflation can be maintained in the single packer by a ball check valve or similar devices. Before expandable packers are run, they are typically filled with liquid and sealed with a plug. In some forms a setting ball may be dropped and tubing pressure applied to set the packer. The pressure may be then increased to shear pins and release the setting ball. Alternatively, pins can be sheared with a sinking bar or a retrievable setting plug may be used. All of these methods of setting expandable packers are well known in the art to which this invention pertains.
Most of the current expandable packers are made with an elastomeric membrane for sealing supported on a metallic structure for mechanical strength. Current expandable packers are assemblies of many different elements such as steel cables, nipples, skirts, and mechanical fibers such as kevlar fibers for anti-extrusion mechanically joined to an elastomeric packer element. The current invention provides an integral composite body allowing the integration of fiber support or metal slats within the integral body to provide extrusion resistance and strength. Since the expansion support is achieved by the laminar location of the support fibers or slats, the mechanical connection to these supporting structures is minimized and the strength of the packer is enhanced.
Often, operators desire to remove a previously set packer to allow access to the well bore. Existing mechanical packer systems can fail to retract after exposure to the high temperatures and pressures of a well bore or production tubing. Another drawback of the existing metallic structure is its susceptibility to corrosion from the fluids encountered in the well bore. The elastomeric membrane in current expandable packers can plastically deform after expansion or break due to excessive bending which may require an anti-extrusion layer between the mechanical reinforcement and the membrane. The present invention with its integral body provides a packer which can be composed of an inner sealing bladder, an integrated mechanical structure, and an outer elastomeric layer for sealing. The support system can be made entirely of a composite material and thus integrates the mechanical support elements within a laminar structure of the composite body.